A mother and daughter were among the three killed in three incidents police believe are linked.
The two women have been named locally as Emma Robertson Coupland and Nicole Anderson.
The mother, 39, was found injured in the car park of University Hospital Crosshouse, near Kilmarnock in East Ayrshire, at around 7.45pm on Thursday but she died at the scene.
In a second incident 20 minutes later on Portland Street, Kilmarnock, Ms Anderson, 24, was stabbed.
Emergency services attended the scene and she was taken to the hospital at Crosshouse, but she later died.
A crash then occurred on the C50 – a minor road between the B7036 and the A76 on the outskirts of Kilmarnock – at around 8.30pm.
The 40-year-old male driver was pronounced dead at the scene.
Friends and family have taken to social media to pay tribute to mother Emma Robertson Coupland and daughter Nicole Anderson.
Nicole's fiancée wrote: "My beautiful wee angel I will love you forever.
"Hoping I could wake up and this all be a dream can’t take it in I’m completely broken."
She later added: "So glad I have all these memories with you. You'll never know how much you mean to me.
"I will love you till the end of time my darling. I will miss that beautiful smile, that wee gorgeous person inside and out.
"You made me the happiest person on this planet daily, until we meet again baby I love you. Sleep tight princess."
Alan Coupland said: "Still not wrapped my head round what happened last night.
"Every time you hear of something terrible happening on here you never imagine it being someone you know let alone family.
"Two genuinely lovely people who never deserved that taken far too soon in life."
He added: "Don't even know what to say, I'll no doubt think of something I wished I'd said later but I'll ask you to tell your loved ones how much they mean to you as you never know what could happen tomorrow."
Ahead of the daily Scottish Government coronavirus briefing at Friday lunchtime, Deputy First Minister John Swinney spoke about the “dreadful” events.
He said: “A tragedy like this would be impossible to understand at any time, but after the events of the past year it is particularly shocking that such an incident has taken place at an NHS hospital.
“An investigation is of course ongoing, however Police Scotland have confirmed that the site at Crosshouse Hospital is secure and it is safe for patients and staff to go there.
“For now I simply want to thank the police officers and all of the medical staff who were involved in the response to this incident for all that they contributed and to express my sympathy to the staff of the hospital for the trauma to which they are having to come to terms.
“And again I want to send my deepest condolences to the family and the friends of those who have been killed.”
First Minister Nicola Sturgeon tweeted: “Dreadful news. My thoughts are with the bereaved.
“Thinking too of everyone at Crosshouse Hospital, already dealing with the tough circumstances of Covid. I’m also grateful to our emergency services. Please continue to follow @policescotland advice.”
My thoughts are with those involved in these very serious incidents in Crosshouse/Kilmarnock. Please help @AyrshirePolice do their job by following the advice to stay away from the areas affected. https://t.co/g2Q3J914o4
— Nicola Sturgeon (@NicolaSturgeon) February 4, 2021
Downing Street said Boris Johnson’s thoughts are with those involved.
A Number 10 spokesman said: “The Prime Minister’s thoughts are with all those involved and he thanks the police and the healthcare staff for their response.”
Scotland’s Health Secretary Jeane Freeman said her thoughts are with all those involved in the incidents in Kilmarnock.
In a statement, she said: “My thoughts are with the family and loved ones of all those affected by last night’s tragic incidents at University Hospital Crosshouse, and elsewhere in Kilmarnock.
“I would also like to extend my sincere thanks to healthcare staff, police and other emergency services involved in dealing with this.
“We are of course offering immediate support to National Health Service colleagues.
“I am also aware that this is an ongoing police investigation and the NHS will be working with Police Scotland to give them full co-operation.”
Horrific incident. Heartbreaking for the families, friends and colleagues of all of those involved - my thoughts with them all. https://t.co/c9Gs4eZEqu
— Humza Yousaf (@HumzaYousaf) February 5, 2021
Scotland’s Justice Secretary Humza Yousaf tweeted: “Horrific incident. Heartbreaking for the families, friends and colleagues of all of those involved – my thoughts with them all.”
Several roads in Kilmarnock town centre remain closed – including Portland Street, West George Street and Garden Street via Hill Street – as well as where the crash occurred, with diversions in place.
An East Ayrshire Council statement said: “Following on from the tragic incidents in and around Kilmarnock last night, our thoughts are with all the families and individuals affected by these events.
“We know our communities will be shocked and saddened by these events, but we wish to reassure them that there is no risk to the general public at this time and we are supporting our colleagues in NHS Ayrshire & Arran and Police Scotland wherever we can.
“As this is an ongoing police matter, we need to keep a number of roads in Kilmarnock town centre closed and diversions are in place here, and on the A76, to allow the investigation to continue, and we thank you for your patience and understanding.”
Police said inquiries so far suggest the incidents are linked and officers are not looking for anyone else as part of their investigation.
Chief Superintendent Faroque Hussain said: “A number of locations remain cordoned off as officers continue to conduct inquiries.
“We are working to confirm the full circumstances of what has happened. If anyone has any information which could assist our inquiries, please do contact us.
“Understandably, people will be shocked by what has happened.
“We are still in the process of establishing the full circumstances, however I would like to reassure people that there is no wider threat to the community.
“Officers will be on patrol and anyone with any concerns can approach these officers.”
The relatives of those involved have been informed.
A statement on Thursday night from police said the incidents are not being treated as terrorist-related.
The hospital was locked down following the first incident, but that was lifted at around 10.30pm when police declared it safe to do so.
On Friday morning, the hospital’s A&E department and main entrance were open and running as normal while two police vans full of officers remained outside with police tape around part of the car park.
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